The present disclosure relates generally to medical devices and, more particularly, to sensors used for sensing physiological parameters of a patient.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring physiological characteristics. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine.
One such monitoring technique is commonly referred to as pulse oximetry. Pulse oximetry may be used to measure various blood flow characteristics, such as the blood-oxygen saturation of hemoglobin in arterial blood and/or the rate of blood pulsations corresponding to each heartbeat of a patient.
The devices based upon pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximeters typically utilize a non-invasive sensor that is placed on or against a patient's tissue that is well perfused with blood, such as a patient's finger, toe, forehead or earlobe. The pulse oximeter sensor emits light and photoelectrically senses the absorption and/or scattering of the light after passage through the perfused tissue. The data collected by the sensor may then be used to calculate one or more of the above physiological characteristics based upon the absorption or scattering of the light. More specifically, the emitted light is typically selected to be of one or more wavelengths that are absorbed or scattered in an amount related to the presence of oxygenated versus deoxygenated hemoglobin in the blood. The amount of light absorbed and/or scattered may then be used to estimate the amount of the oxygen in the tissue using various algorithms.
During use, the performance of a pulse oximetry sensor may rely on there being substantial contact between the surface of the patient's tissue (i.e., skin or nail bed) and the light emitting and detecting sensors. Good contact between the sensor and the tissue helps prevent light from scattering before being detected by the detecting sensor and helps to prevent additional light, i.e., ambient light or other light not emitted by the sensor, from reaching the detector. For example, a sensor may be clipped about a patients finger tip with the emitter placed on the finger nail, and the detector placed on the under side of the finger tip. In this configuration, the sensor should clip about the finger with enough force to eliminate or reduce the gap between the emitter and the finger nail, as well as eliminate the gap between the detector and the underside of the finger tip. By providing a sufficiently tight fit, the emitted light may travel directly through the tissue of the finger and be detected without additional light being introduced or the emitted light being scattered. Further, the sufficiently tight fit may reduce the likelihood of the pulse oximetry sensor moving relative to the patient's tissue and/or falling off of the patient. However, in practice, anatomic variation between individuals may make achieving such a tight fit with good contact difficult using standardized sensor sizes.